Radiolabeled polyoxometalate clusters: Kidney dysfunction evaluation and tumor diagnosis by positron emission tomography imaging

Nano-enzyme functionalized hydrogels promote diabetic wound healing through immune microenvironment modulation

Non-healing diabetic wounds often culminate in amputation and mortality. The main pathophysiological features in diabetic wounds involve the accumulation of M1-type macrophages and excessive oxidative stress. In this study, we engineered a nano-enzyme functionalized hydrogel by incorporating a magnesium ion-doped molybdenum-based polymetallic oxide (Mg-POM), a novel bioactive nano-enzyme, into a GelMA hydrogel, to obtain the GelMA@Mg-POM system to enhance diabetic wound healing. GelMA@Mg-POM was crosslinked using UV light, yielding a hydrogel with a uniformly porous three-dimensional mesh structure. In vitro experiments showed that GelMA@Mg-POM extraction significantly enhanced human umbilical vein endothelial cell (HUVEC) migration, scavenged ROS, improved the inflammatory microenvironment, induced macrophage reprogramming towards M2, and promoted HUVEC regeneration of CD31 and fibroblast regeneration of type I collagen. In in vivo experiments, diabetic rat wounds treated with GelMA@Mg-POM displayed enhanced granulation tissue genesis and collagen production, as evidenced by HE and Masson staining. Immunohistochemistry demonstrated the ability of GelMA@Mg-POM to mitigate macrophage-associated inflammatory responses and promote angiogenesis. Overall, these findings suggest that GelMA@Mg-POM holds significant promise as a biomaterial for treating diabetic wounds.

Highly Sensitive Early Diagnosis of Kidney Damage Using Renal Clearable Zwitterion-Coated Ferrite Nanoprobe via Magnetic Resonance Imaging In Vivo

Iron oxide nanoprobes exhibit substantial potential in magnetic resonance imaging (MRI) of kidney diseases and can eliminate the nephrotoxicity of gadolinium-based contrast agents (GBCAs). Nevertheless, there is an extreme shortage of highly sensitive and renal clearable iron oxide nanoprobes suitable for early kidney damage detection through MRI. Herein, a renal clearable ultra-small ferrite nanoprobe (UMFNPs@ZDS) is proposed for highly sensitive early diagnosis of kidney damage via structural and functional MRI in vivo for the first time. The nanoprobe comprises a ferrite core coated with a zwitterionic layer, and possesses a high T1 relaxivity (12.52 mm-1s-1), a small hydrodynamic size (6.43 nm), remarkable water solubility, excellent biocompatibility, and impressive renal clearable ability. In a rat model of unilateral ureteral obstruction (UUO), the nanoprobe-based MRI can not only accurately visualize the locations of renal injury, but also provide comprehensive functional data including peak value, peak time, relative renal function (RRF), and clearance percentage via MRI. The findings prove the immense potential of ferrite nanoprobes as a superior alternative to GBCAs for the early diagnosis of kidney damage.

Noninvasive Diagnosis of Kidney Dysfunction Using a Small-Molecule Manganese-Based Magnetic Resonance Imaging Probe

Contrast-enhanced magnetic resonance imaging (CE-MRI) is a promising approach for the diagnosis of kidney diseases. However, safety concerns, including nephrogenic systemic fibrosis, limit the administration of gadolinium (Gd)-based contrast agents (GBCAs) in patients who suffer from renal impairment. Meanwhile, nanomaterials meet biosafety concerns because of their long-term retention in the body. Herein, we propose a small-molecule manganese-based imaging probe Mn-PhDTA as an alternative to GBCAs to assess renal insufficiency for the first time. Mn-PhDTA was synthesized via a simple three-step reaction with a total yield of up to 33.6%, and a gram-scale synthesis can be realized. Mn-PhDTA has an r1 relaxivity of 2.72 mM-1 s-1 at 3.0 T and superior kinetic inertness over Gd-DTPA and Mn-EDTA with a dissociation time of 60 min in the presence of excess Zn2+. In vivo and in vitro experiments demonstrate their good stability and biocompatibility. In the unilateral ureteral obstruction rats, Mn-PhDTA provided significant MR signal enhancement, enabled distinguishing structure changes between the normal and damaged kidneys, and evaluated the renal function at different injured stages. Mn-PhDTA could act as a potential MRI contrast agent candidate for the replacement of GBCAs in the early detection of kidney dysfunction and analysis of kidney disease progression.

Noninvasive Assessment of Kidney Injury by Combining Structure and Function Using Artificial Intelligence-Based Manganese-Enhanced Magnetic Resonance Imaging

Contrast-enhanced magnetic resonance imaging (MRI) is seriously limited in kidney injury detection due to the nephrotoxicity of clinically used gadolinium-based contrast agents. Herein, we propose a noninvasive method for the assessment of kidney injury by combining structure and function information based on manganese (Mn)-enhanced MRI for the first time. As a proof of concept, the Mn-melanin nanoprobe with good biocompatibility and excellent T1 relaxivity is applied in MRI of a unilateral ureteral obstruction mice model. The abundant renal structure and function information is obtained through qualitative and quantitative analysis of MR images, and a brand new comprehensive assessment framework is proposed to precisely identify the degree of kidney injury successfully. Our study demonstrates that Mn-enhanced MRI is a promising approach for the highly sensitive and biosafe assessment of kidney injury in vivo.

The application of nanotechnology in kidney transplantation

Kidney transplantation is a crucial treatment option for end-stage renal disease patients, but challenges related to graft function, rejection and immunosuppressant side effects persist. This review highlights the potential of nanotechnology in addressing these challenges. Nanotechnology offers innovative solutions to enhance organ preservation, evaluate graft function, mitigate ischemia-reperfusion injury and improve drug delivery for immunosuppressants. The integration of nanotechnology holds promise for improving outcomes in kidney transplantation.

Injectable hydrogels for personalized cancer immunotherapies

The field of cancer immunotherapy has shown significant growth, and researchers are now focusing on effective strategies to enhance and prolong local immunomodulation. Injectable hydrogels (IHs) have emerged as versatile platforms for encapsulating and controlling the release of small molecules and cells, drawing significant attention for their potential to enhance antitumor immune responses while inhibiting metastasis and recurrence. IHs delivering natural killer (NK) cells, T cells, and antigen-presenting cells (APCs) offer a viable method for treating cancer. Indeed, it can bypass the extracellular matrix and gradually release small molecules or cells into the tumor microenvironment, thereby boosting immune responses against cancer cells. This review provides an overview of the recent advancements in cancer immunotherapy using IHs for delivering NK cells, T cells, APCs, chemoimmunotherapy, radio-immunotherapy, and photothermal-immunotherapy. First, we introduce IHs as a delivery matrix, then summarize their applications for the local delivery of small molecules and immune cells to elicit robust anticancer immune responses. Additionally, we discuss recent progress in IHs systems used for local combination therapy, including chemoimmunotherapy, radio-immunotherapy, photothermal-immunotherapy, photodynamic-immunotherapy, and gene-immunotherapy. By comprehensively examining the utilization of IHs in cancer immunotherapy, this review aims to highlight the potential of IHs as effective carriers for immunotherapy delivery, facilitating the development of innovative strategies for cancer treatment. In addition, we demonstrate that using hydrogel-based platforms for the targeted delivery of immune cells, such as NK cells, T cells, and dendritic cells (DCs), has remarkable potential in cancer therapy. These innovative approaches have yielded substantial reductions in tumor growth, showcasing the ability of hydrogels to enhance the efficacy of immune-based treatments. STATEMENT OF SIGNIFICANCE: As cancer immunotherapy continues to expand, the mode of therapeutic agent delivery becomes increasingly critical. This review spotlights the forward-looking progress of IHs, emphasizing their potential to revolutionize localized immunotherapy delivery. By efficiently encapsulating and controlling the release of essential immune components such as T cells, NK cells, APCs, and various therapeutic agents, IHs offer a pioneering pathway to amplify immune reactions, moderate metastasis, and reduce recurrence. Their adaptability further shines when considering their role in emerging combination therapies, including chemoimmunotherapy, radio-immunotherapy, and photothermal-immunotherapy. Understanding IHs' significance in cancer therapy is essential, suggesting a shift in cancer treatment dynamics and heralding a novel period of focused, enduring, and powerful therapeutic strategies.

Endometriosis-targeted MRI imaging using bevacizumab-modified nanoparticles aimed at vascular endothelial growth factor

Endometriosis is a tumor-like disease with high recurrence. In this case, the accurate imaging-based diagnosis of endometriosis can help clinicians eradicate it by improving their surgical plan. However, although contrast agents can improve the visibility of the tissue of interest in vivo via magnetic resonance imaging (MRI), the lack of biomarkers in endometriosis hinders the development of agents for its targeted imaging and diagnosis. Herein, aiming at the enriched vascular endothelial growth factor (VEGF) in endometriosis, we developed a targeting MRI contrast agent modified with bevacizumab, i.e., NaGdF₄@PEG@bevacizumab-Cy5.5 nanoparticles (NPBCNs), to detect endometriosis. NPBCNs showed negligible cytotoxicity and high affinity towards VEGF in endometrial cells in vitro. Furthermore, NPBCNs generated a strong signal enhancement in vivo in endometriosis lesions in rats in T₁-weighted images via MRI at 3 days post-injection, as confirmed by the histopathological staining results and fluorescence imaging on the same day. Our approach can enable NPBCNs to target endometriosis effectively, thus avoiding missed diagnoses.

A Smart Benzothiazole-Based Conjugated Polymer Nanoplatform with Multistimuli Response for Enhanced Synergistic Chemo-Photothermal Cancer Therapy

The combination of chemotherapy and phototherapy has received tremendous attention in multimodal cancer therapy. However, satisfactory therapeutic outcomes of chemo-photothermal therapy (chemo-PTT) still remain challenging. Herein, a biocompatible smart nanoplatform based on benzothiazole-linked conjugated polymer nanoparticles (CPNs) is rationally designed, for effectively loading doxorubicin (DOX) and Mo-based polyoxometalate (POM) through both dynamic chemical bond and intermolecular interactions, with an expectation to obtain new anticancer drugs with multiple stimulated responses to the tumor microenvironment (TME) and external laser irradiation. Controlled drug release of DOX from the obtained nanoformulation (CPNs-DOX-PEG-cRGD-BSA@POM) triggered by both endogenous stimulations (GSH and low pH) and exogenous laser irradiation has been well demonstrated by pharmacodynamics investigations. More intriguingly, incorporating POM into the nanoplatform not only enables the nanomedicine to achieve mild hyperthermia but also makes it exhibit self-assembly behavior in acidic TME, producing enhanced tumor retention. Benefiting from the versatile functions, the prepared CPNs-DOX-PEG-cRGD-BSA@POM exhibited excellent tumor targeting and therapeutic effects in murine xenografted models, showing great potential in practical cancer therapy.

pH-sensitive molybdenum (Mo)-based polyoxometalate nanoclusters have therapeutic efficacy in inflammatory bowel disease by counteracting ferroptosis

Current therapeutic drugs for ulcerative colitis (UC) remained inadequate due to drug dependence and unacceptable adverse events. Reactive oxygen species (ROS) played a critical role in the occurrence and development of UC, which most likely benefited from treatment in scavenging ROS. In this study, we developed a pH-sensitive molybdenum-based polyoxometalate (POM) nanocluster, which might contribute to site specific colonic delivery and enhance systemic efficacy of UC treatment. Our results demonstrated that POM displayed robust ROS scavenging ability in vitro. POM could significantly alleviate the enteric symptoms and inflammatory indicators in DSS-induced UC mouse models. Flow cytometry showed an effective diminishment of macrophages, neutrophils and T cells infiltration after POM administration in UC models. Also, for the first time, we demonstrated that POM interfered with metabolic pathway associated to oxidative stress and partially improved the abnormal production of intestinal metabolites in UC to some extent. Benefiting from the ROS scavenging ability, POM attenuated ferroptosis in DSS induced UC, as evidenced by increase of GSH, down-expression of GPX4 and improvement in mitochondrial morphological changes. Meanwhile, there were no side effects on normal tissues. Thus, our powerful therapeutic effects pioneered the application of POM for safer and more effective POM-based UC therapy.

Acoustic-Based Theranostic Probes Activated by Tumor Microenvironment for Accurate Tumor Diagnosis and Assisted Tumor Therapy

Acoustic-based imaging techniques, including ultrasonography and photoacoustic imaging, are powerful noninvasive approaches for tumor imaging owing to sound transmission facilitation, deep tissue penetration, and high spatiotemporal resolution. Usually, imaging modes were classified into "always-on" mode and "activatable" mode. Conventional "always-on" acoustic-based probes often have difficulty distinguishing lesion regions of interest from surrounding healthy tissues due to poor target-to-background signal ratios. As compared, activatable probes have attracted attention with improved sensitivity, which can boost or amplify imaging signals only in response to specific biomolecular recognition or interactions. The tumor microenvironment (TME) exhibits abnormal physiological conditions that can be used to identify tumor sections from normal tissues. Various types of organic dyes and biomaterials can react with TME, leading to obvious changes in their optical properties. The TME also affects the self-assembly or aggregation state of nanoparticles, which can be used to design activatable imaging probes. Moreover, acoustic-based imaging probes and therapeutic agents can be coencapsulated into one nanocarrier to develop nanotheranostic probes, achieving tumor imaging and cooperative therapy. Satisfactorily, ultrasound waves not only accelerate the release of encapsulated therapeutic agents but also activate therapeutic agents to exert or enhance their therapeutic performance. Meanwhile, various photoacoustic probes can convert photon energy into heat under irradiation, achieving photoacoustic imaging and cooperative photothermal therapy. In this review, we focus on the recently developed TME-triggered ultrasound and photoacoustic theranostic probes for precise tumor imaging and targeted tumor therapy.

Boosting Simultaneous Uranium Decorporation and Reactive Oxygen Species Scavenging Efficiency by Lacunary Polyoxometalates

The chemical toxicity and the oxidative stress induced by the internal exposure of uranium is responsible for the long-term adverse effect of in vivo contamination of uranium. An agent with simultaneous removal capability of uranium and excess reactive oxygen species (ROS) is highly desired. Herein, the lacunary Keggin-type polyoxometalate (POM) is demonstrated to selectively bind with uranyl ions in the presence of excess essential divalent ions and exhibits a compelling ROS scavenging efficiency of 78.8%. In vivo uranium decorporation assays illustrate the uranium sequestration efficiencies of 74.0%, 49.4%, and 37.1% from kidneys by prophylactic, prompt, and delayed administration of lacunary POM solution, respectively. The superior ROS quenching and uranium removal performance in comparison with all reported bifunctional agents endow lacunary polyoxometalates as novel agents to effectively protect people from injuries caused by the internal exposure of actinides.

Systemic and single cell level responses to 1 nm size biomaterials demonstrate distinct biological effects revealed by multi-omics atlas

Although ultra-small nanoclusters (USNCs, < 2 nm) have immense application capabilities in biomedicine, the investigation on body-wide organ responses towards USNCs is scant. Here, applying a novel strategy of single-cell mass cytometry combined with Nano Genome Atlas of multi-tissues, we systematically evaluate the interactions between the host and calcium phosphate (CaP) USNCs at the organism level. Combining single-cell mass cytometry, and magnetic luminex assay results, we identify dynamic immune responses to CaP USNCs at the single cell resolution. The innate immune is initially activated and followed by adaptive immune activation, as evidenced by dynamic immune cells proportions. Furthermore, using Nano Genome Atlas of multi-tissues, we uncover CaP USNCs induce stronger activation of the immune responses in the cartilage and subchondral bone among the five local tissues while promote metabolic activities in the liver and kidney. Moreover, based on the immunological response profiles, histological evaluation of major organs and local tissue, and a body-wide transcriptomics, we demonstrate that CaP USNCs are not more hazardous than the Food and Drug Administration-approved CaP nanoparticles after 14 days of injection. Our findings provide valuable information on the future clinical applications of USNCs and introduce an innovative strategy to decipher the whole body response to implants.

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We described a new strategy to facilitate the analysis of body-wide systemic responses of CaP USNCs in vivo.

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At single-cell resolution, we decoded a dynamic immune atlas of CaP USNCs in the blood.

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Based on the body-wide transcriptomics view, the biological effect of CaP USNCs is organ/tissue specific.

Self-assembly of DNA nanostructure containing cell-specific aptamer as a precise drug delivery system for cancer therapy in non-small cell lung cancer

Background

As the most common subtype in lung cancer, the precise and efficient treatment for non-small cell lung cancer (NSCLC) remains an outstanding challenge owing to early metastasis and poor prognosis. Chemotherapy, the most commonly used treatment modality, is a difficult choice for many cancer patients due to insufficient drug accumulation in tumor sites and severe systemic side-effects. In this study, we constructed a cell-specific aptamer-modified DNA nanostructure (Apt-NS) as a targeting drug delivery system achieving the precision therapy for lung cancer.

Methods

The synthesis of DNA nanostructure and its stability were evaluated using gel electrophoresis. The targeting properties and internalization mechanism were investigated via flow cytometry and confocal analyses. Drug loading, release, and targeted drug delivery were determined by fluorescence detection, Zeta potentials assay, and confocal imaging. CCK8 assays, colony formation, cell apoptosis, metastasis analyses and in vivo experiments were conducted to assess the biological functions of DNA nanostructure.

Results

Self-assembled DNA nanoparticles (Apt-NS) had excellent stability to serum and DNase I and the ability to specifically recognize A549 cells. Upon specific binding, the drug-loaded nanoparticles (Apt-NS-DOX) were internalized into target cells by clathrin-mediated endocytosis. Subsequently, DOX could be released from Apt-NS-DOX based on the degradation of the lysosome. Apt-NS-DOX exerted significant suppression of cell proliferation, invasion and migration, and also enhanced cell apoptosis due to the excellent performance of drug delivery and intracellular release, while maintaining a superior biosafety. In addition, the antitumor effects of Apt-NS-DOX were further confirmed using in vivo models.

Conclusions

Our study provided cell-specific aptamer-modified DNA nanostructures as a drug-delivery system targeting A549 cells, which could precisely and efficiently transport chemotherapeutic drug into tumor cells, exerting enhanced antineoplastic efficacy. These findings highlight that DNA nanostructure serving as an ideal drug delivery system in cancer treatment appears great promise in biomedical applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01701-5.

Polyoxometalate-based nanocomposites for antitumor and antibacterial applications

Polyoxometalates (POMs), as emerging inorganic metal oxides, have been shown to have significant biological activity and great medicinal value. Nowadays, biologically active POM-based organic-inorganic hybrid materials have become the next generation of antibacterial and anticancer drugs because of their customizable molecular structures related to their highly enhanced antitumor activity and reduced toxicity to healthy cells. In this review, the current developed strategies with POM-based materials for the purpose of antibacterial and anticancer activities from different action principles inducing cell death and hyperpolarization, cell plasma membrane destruction, interference with bacterial respiratory chain and inhibiting bacterial growth are overviewed. Moreover, specific interactions between POM-based materials and biomolecules are highlighted for a better understanding of their antibacterial and anticancer mechanisms. POMs have great promise as next-generation antibacterial and anticancer drugs, and this review will provide a valuable systematic reference for the further development of POM-based nanomaterials.

Injectable Hydrogel-Based Combination Cancer Immunotherapy for Overcoming Localized Therapeutic Efficacy

Various immunotherapeutic agents that can elicit antitumor immune responses have recently been developed with the potential for improved efficacy in treating cancer. However, insufficient delivery efficiency at the tumor site, along with severe side effects after systemic administration of these anticancer agents, have hindered their therapeutic application in cancer immunotherapy. Hydrogels that can be directly injected into tumor sites have been developed to help modulate or elicit antitumor responses. Based on the biocompatibility, degradability, and controllable mechanochemical properties of these injectable hydrogels, various types of immunotherapeutic agents, such as hydrophobic anticancer drugs, cytokines, antigens, and adjuvants, have been easily and effectively encapsulated, resulting in the successful elicitation of antitumor immune responses and the retention of long-term immunotherapeutic efficacy following administration. This review summarizes recent advances in combination immunotherapy involving injectable hydrogel-based chemoimmunotherapy, photoimmunotherapy, and radioimmunotherapy. Finally, we briefly discuss the current limitations and future perspectives on injectable hydrogels for the effective combination immunotherapy of tumors.

In Vitro Anticancer Ability of Nano Fluorescent 111 In‐MIL‐68/PEG‐FA on Hela Cells

In past decades, nanoscale metal-organic frameworks (NMOFs) have drawn more and more attention in multimodal imaging and targeting therapy of various malignant cancers. Here, we proposed to dope ¹¹¹ In into fluorescent In-based NMOFs (In-MIL-68-NH₂ ), with an attempt to prepare a new nanomedicine with great anticancer potential. As a proof of concept, the obtained NMOF (In-MIL-68/PEG-FA) with targeting motifs is able to act as a fluorescent probe to achieve Hela cell imaging. Moreover, the Auger electron emitter ¹¹¹ In built in corresponding radioactive NMOF (¹¹¹ In-MIL-68/PEG-FA) can bring clear damage to cancer cells, leading to a high cell killing rate of 59.3 % within 48 h. In addition, the cell cycle presented a significant dose-dependent G2/M inhibiting mode, which indicates that ¹¹¹ In-MIL-68/PEG-FA has the ability to facilitate the cancer cells to enter apoptotic program. This work demonstrated the potential of ¹¹¹ In-labelled NMOFs in specific killings of cancer cells, providing a new approach to develop nanomedicines with theranostic function.

Injectable hydrogel platform with biodegradable Dawson-type polyoxometalate and R848 for combinational photothermal-immunotherapy of cancer

Photothermal therapy (PTT) is a powerful strategy for cancer treatment with minimal invasiveness but still limited by lack of long-term efficacy against tumor recurrence and toxicity concerns about the slow biodegradability of the PTT agents. Herein, an injectable hydrogel platform (R848/POM@GG) of gellan gum co-loaded with Dawson-type {P₂Mo₁₈} polyoxometalate (POM) and Toll-like receptors agonist resiquimod (R848) is developed for combinational photothermal-immunotherapy of cancer. The POM-based gellan gum hydrogel (POM@GG) exhibits high photothermal conversion efficiency (63.1%) at a safe power density of 0.3 W cm^-2 and good photostability during five cycles. By further incorporation of R848, the obtained R848/POM@GG exerts synergetic photothermal-immunotherapy on solid tumors, giving a high tumor inhibition rate of 99.3% and negligible lung metastases in the breast cancer mice models. A strong antitumor immune system with significantly elevated TNF-α, IL-2, and IL-6 levels is activated by R848. Additionally, the POM clusters gradually degrade to nontoxic molybdate in the physiological environment. Overall, the injectable hydrogel platform of R848/POM@GG has great translational potential for localized antitumor treatments.

A urinary drug-disposing approach as an alternative to intravesical chemotherapy for treating non-muscle invasive bladder cancer

The standard treatment of non-muscle invasive bladder cancer (NMIBC) is transurethral resection of the tumors, followed by intravesical therapy (IT), which comprises a direct instillation of a solution of Bacillus Calmette-Guérin vaccine or chemotherapy into the bladder. However, the recurrence rate in this disease remains unacceptably high. IT is a local treatment that fails to reach tumors developed in the upper urinary tract (ureter and renal pelvis). The catheterization procedure required for IT is invasive, painful, and poses an increased infection risk resulting in poor patient quality of life and compliance. There is an unmet need for a potent, comprehensive, and non-invasive option. Without chemical modifications, peptides are rapidly removed by renal clearance. This "shortcoming" can be advantageous when used as a drug carrier for directing therapy to NMIBC. Here we develop a urinary drug-disposing (UDD) approach to improve NMIBC treatment. A 12-amino acid bio-inert peptide (Bdd) that can be exclusively eliminated via renal filtration was generated for delivering the microtubule inhibitor DM1 to NMIBC with minimal non-specific accumulation in other organs. The UDD approach prolonged survival of mice bearing human bladder tumors. Unlike IT, the treatment was given non-invasively (intravenously). Furthermore, it was more effective at suppressing tumor growth than clinically used IT (mitomycin) and safer than free DM1. The application of this urinary drug-disposing approach to treat kidney tumors and deliver other drugs such as doxorubicin was also demonstrated. Overall, the rapid renal clearance of peptides can be exploited to direct cancer therapies to the urinary system.

Nanotechnology, Nanomedicine, and the Kidney

The kidneys are vital organs performing several essential functions. Their primary function is the filtration of blood and the removal of metabolic waste products as well as fluid homeostasis. Renal filtration is the main pathway for drug removal, highlighting the importance of this organ to the growing field of nanomedicine. The kidneys (i) have a key role in the transport and clearance of nanoparticles (NPs), (ii) are exposed to potential NPs’ toxicity, and (iii) are the targets of diseases that nanomedicine can study, detect, and treat. In this review, we aim to summarize the latest research on kidney-nanoparticle interaction. We first give a brief overview of the kidney’s anatomy and renal filtration, describe how nanoparticle characteristics influence their renal clearance, and the approaches taken to image and treat the kidney, including drug delivery and tissue engineering. Finally, we discuss the future and some of the challenges faced by nanomedicine.

Alkaline phosphatase-triggered self-assembly of near-infrared nanoparticles for the enhanced photoacoustic imaging of tumors

In this chapter, we discuss the need for the development of enzyme-activatable probes in the field of tumor-targeted photoacoustic (PA) imaging, then we give a brief description of the innovation of designing alkaline phosphatase (ALP)-activatable probes for PA imaging. After that, we provide detailed protocols for the syntheses and characterizations of a near-infrared photoacoustic imaging probe, 1P, developed in our research group. With this tool, 1P could form nanoparticles 1-NPs under the catalysis of ALP and thus could be used to enhance PA imaging both in vitro and in vivo.

Rational design of nanomedicine for photothermal-chemodynamic bimodal cancer therapy

Given the diversity, complexity, and heterogeneity of persistent tumors, traditional nanoscale monotherapeutic systems suffer from dissatisfactory curative efficiency with incidence of metastasis or relapse. In parallel, the trend of clinical research on the basis of nanomedicines has increasingly shifted from monotherapy toward combinatorial therapy for admirable synergetic performances. In this regard, cutting-edge nanomedicines harnessing photothermal-chemodynamic bimodal therapy (PTT/CDT) have opened up a highly-efficient and relatively-safe cancer theranostic paradigm. Still, the integration of PTT/CDT functional units into one nanomedicine remains a herculean but meaningful task to achieve notable super-additive effects. This review aims to elucidate underlying synergistic interactions of PTT/CDT and highlight intriguing designs of nanomedicines for PTT/CDT including nanomaterial selection, performance optimization, multimodal therapy, visualization strategies, and targeting strategies. Furthermore, an outlook on further improvements of PTT/CDT is provided, emphasizing significant scientific issues that require remediation for clinical translation. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Nanomedicines for Renal Management: From Imaging to Treatment

Nanomedicine has benefited from recent advances in chemistry and biomedical engineering to produce nanoscale materials as theranostic agents. Well-designed nanomaterials may present optimal biological properties, influencing circulation, retention, and excretion for imaging and treatment of various diseases. As the understanding of nanomedicine pharmacokinetics expands continuously, efficient renal clearance of nanomedicines can significantly increase the signal-to-background ratio for precision diagnosis and lower potential toxicity for improved treatment. Studies on nanomaterial-kidney interactions have led to many novel findings on the underlying principles of nanomaterial renal clearance, targeting, and accumulation. In return, the optimized nanomedicines confer significant benefits to the detection and treatment of kidney dysfunction.In this Account, we present an overview of recent progress in the development of nanomaterials for kidney theranostics, aiming to speed up translation and expand possible applications. We start by introducing biological structures of the kidney and their influence on renal targeting, retention, and clearance. Several key factors regarding renal accumulation and excretion, including nanomaterial types, sizes, and shapes, surface charges, and chemical modifications, are identified and discussed. Next, we highlight our recent efforts investigating kidney-interacting nanomaterials and introduce representative nanomedicines for imaging and treatment of kidney diseases. Multiple renal-clearable and renal-accumulating nanomedicines were devised for kidney function imaging. By employing renal-clearable nanomedicines, including gold nanoparticles, porphyrin polymers, DNA frameworks, and polyoxometalate clusters, we were able to noninvasively evaluate split renal function in healthy and diseased mice. Further engineering of renal-accumulating nanosystems has shifted attention from renal diagnosis to precision kidney protection. Many biocompatible nanomedicines, such as DNA origami, selenium-doped carbon quantum dots, melanin nanoparticles, and black phosphorus have all played essential roles in diminishing excessive reactive oxygen species for kidney treatment and protection. Finally, we discuss the challenges and perspectives of nanomaterials for renal care, their future clinical translation, and how they may affect the current landscape of clinical practices. We believe that this Account updates our current understanding of nanomaterial-kidney interactions for further design and control of nanomedicines for specific kidney diagnosis and treatment. This timely Account will generate broad interest in integrating nanotechnology and nanomaterial-biological interaction for state-of-the-art theranostics of renal diseases.

Combinatorial discovery of Mo-based polyoxometalate clusters for tumor photothermal therapy and normal cell protection

Molybdenum (Mo)-based polyoxometalate clusters can kill cancer cells selectively by PTT assay and protect the normal cells by scavenging ROS effectively.

Intrathecal Administration of Nanoclusters for Protecting Neurons against Oxidative Stress in Cerebral Ischemia/Reperfusion Injury

Oxidative stress is one of the important mechanisms in cerebral ischemia/reperfusion (I/R) injury. Antioxidants with high brain accumulation are highly desired to help prevent cerebral I/R injury. Herein, intrathecal injection of polyoxometalate (POM) nanoclusters as nano-antioxidants with preferential brain uptake were applied for neuronal protection in cerebral I/R injury. Using powerful positron emission tomography imaging, the uptake of nano-antioxidants in the brain was non-invasively and real-timely monitored. Our results demonstrated that POM nanoclusters rapidly reached the ischemic penumbra after intrathecal injection and effectively scavenged reactive oxygen species (ROS) for inhibiting oxidative stress. The infarct size was reduced, and neurological function was restored in cerebral I/R injury rat models. As a proof-of-concept, the intrathecal injection of nano-antioxidants is an excellent therapeutic strategy to ameliorate cerebral I/R injury.

Smart H2S-Triggered/Therapeutic System (SHTS)-Based Nanomedicine

Hydrogen sulfide (H2S) is of vital importance in several biological and physical processes. The significance of H2S-specific detection and monitoring is emphasized by its elevated levels in various diseases such as cancer. Nanotechnology enhances the performance of chemical sensing nanoprobes due to the enhanced efficiency and sensitivity. Recently, extensive research efforts have been dedicated to developing novel smart H2S-triggered/therapeutic system (SHTS) nanoplatforms for H2S-activated sensing, imaging, and therapy. Herein, the latest SHTS-based nanomaterials are summarized and discussed in detail. In addition, therapeutic strategies mediated by endogenous H2S as a trigger or exogenous H2S delivery are also included. A comprehensive understanding of the current status of SHTS-based strategies will greatly facilitate innovation in this field. Lastly, the challenges and key issues related to the design and development of SHTS-based nanomaterials (e.g., morphology, surface modification, therapeutic strategies, appropriate application, and selection of nanomaterials) are outlined.

Mo2 C-Derived Polyoxometalate for NIR-II Photoacoustic Imaging-Guided Chemodynamic/Photothermal Synergistic Therapy

To overcome the current limitations of chemodynamic therapy (CDT), a Mo₂ C-derived polyoxometalate (POM) is readily synthesized as a new CDT agent. It permits synergistic chemodynamic and photothermal therapy operating in the second near-infrared (NIR-II) biological transparent window for deep tissue penetration. POM aggregated in an acidic tumor micro-environment (TME) whereby enables specific tumor targeting. In addition to the strong ability to produce singlet oxygen (¹ O₂ ) presumably via Russell mechanism, its excellent photothermal conversion enhances the CDT effect, offers additional tumor ablation modality, and permits NIR-II photoacoustic imaging. Benefitting from the reversible redox property of molybdenum, the theranostics based on POM can escape from the antioxidant defense system. Moreover, combining the specific responsiveness to TME and localized laser irradiation, side-effects shall be largely avoided.

Photothermal therapy and photoacoustic imaging via nanotheranostics in fighting cancer

The nonradiative conversion of light energy into heat (photothermal therapy, PTT) or sound energy (photoacoustic imaging, PAI) has been intensively investigated for the treatment and diagnosis of cancer, respectively. By taking advantage of nanocarriers, both imaging and therapeutic functions together with enhanced tumour accumulation have been thoroughly studied to improve the pre-clinical efficiency of PAI and PTT. In this review, we first summarize the development of inorganic and organic nano photothermal transduction agents (PTAs) and strategies for improving the PTT outcomes, including applying appropriate laser dosage, guiding the treatment via imaging techniques, developing PTAs with absorption in the second NIR window, increasing photothermal conversion efficiency (PCE), and also increasing the accumulation of PTAs in tumours. Second, we introduce the advantages of combining PTT with other therapies in cancer treatment. Third, the emerging applications of PAI in cancer-related research are exemplified. Finally, the perspectives and challenges of PTT and PAI for combating cancer, especially regarding their clinical translation, are discussed. We believe that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve our ability to combat cancers.

A smart tumor microenvironment responsive nanoplatform based on upconversion nanoparticles for efficient multimodal imaging guided therapy

A smart tumor microenvironment responsive theranostic nanoplatform USPDF for UCL/CT dual-mode imaging and combination of chemotherapy and photothermal therapy.

Molybdenum-based nanoclusters act as antioxidants and ameliorate acute kidney injury in mice

Acute kidney injury (AKI) is a common reactive oxygen species (ROS)-related renal disease that causes numerous deaths annually, yet only supportive treatment is currently available in the clinics. Development of antioxidants with high accumulation rates in kidneys is highly desired to help prevent AKI. Here we report molybdenum-based polyoxometalate (POM) nanoclusters with preferential renal uptake as novel nano-antioxidants for kidney protection. These POM nanoclusters, with a readily variable valence state of molybdenum ions, possess the capability to scavenge detrimental ROS. Our results demonstrate that POM nanoclusters can efficiently alleviate clinical symptoms in mice subjected to AKI, as verified by dynamic PET imaging with ⁶⁸Ga-EDTA, serum tests, kidney tissue staining, and biomarkers detection in the kidneys. The protective effect of POM nanoclusters against AKI in living animals suggests exploring their use for the treatment of AKI patients, as well as patients with other ROS-related diseases.

There are currently no effective therapies available for acute kidney injury (AKI). Here the authors generate molybdenum-based polyoxometalate nanoclusters and show that these have preferential renal uptake and can ameliorate AKI pathology in mice by scavenging reactive oxygen species.

Alkaline Phosphatase-Triggered Self-Assembly of Near-Infrared Nanoparticles for the Enhanced Photoacoustic Imaging of Tumors

Photoacoustic (PA) imaging is advantageous for the diagnosis of superficial cancer with high spatial resolution. However, to the best of our knowledge, using an alkaline phosphatase (ALP)-activatable probe for the enhanced PA imaging of tumors has not been reported. In this work, we rationally designed a NIR probe IR775-Phe-Phe-Tyr(H₂PO₃)-OH (1P) for PA imaging ALP activity in vitro and in tumor. Under the catalysis of ALP, 1P was efficiently converted to IR775-Phe-Phe-Tyr-OH (1), which self-assembled into the nanoparticles 1-NPs. The formation of 1-NPs induced a 6.4-fold enhancement of the 795 nm PA signal of 1P. In vivo tumor PA imaging results indicated that, compared to that in the ALP inhibitor-treated control group, PA contrast in the experimental group enhanced 2.3 folds at 4 h after 1P injection. By replacing the Phe-Phe-Tyr(H₂PO₃)-OH motif in 1P with other enzyme-cleavable ones, we hope that more PA probes could be developed for the precise diagnoses of their corresponding cancers in the near future.

Self-assembling supramolecular dendrimer nanosystem for PET imaging of tumors

Nanotechnology-based imaging is expected to bring breakthroughs in cancer diagnosis by improving imaging sensitivity and specificity while reducing toxicity. Here, we developed an innovative nanosystem for positron emission tomography (PET) imaging based on a self-assembling amphiphilic dendrimer. This dendrimer assembled spontaneously into uniform supramolecular nanomicelles with abundant PET reporting units on the surface. By harnessing both dendrimeric multivalence and the “enhanced permeation and retention” (EPR) effect, this dendrimer nanosystem effectively accumulated in tumors, leading to exceedingly sensitive and specific imaging of various tumors, especially those that are otherwise undetectable using the clinical gold reference 2-fluorodeoxyglucose ([¹⁸F]FDG). This study illustrates the power of nanotechnology based on self-assembling dendrimers to provide an effective platform for bioimaging and related biomedical applications.

Bioimaging plays an important role in cancer diagnosis and treatment. However, imaging sensitivity and specificity still constitute key challenges. Nanotechnology-based imaging is particularly promising for overcoming these limitations because nanosized imaging agents can specifically home in on tumors via the “enhanced permeation and retention” (EPR) effect, thus resulting in enhanced imaging sensitivity and specificity. Here, we report an original nanosystem for positron emission tomography (PET) imaging based on an amphiphilic dendrimer, which bears multiple PET reporting units at the terminals. This dendrimer is able to self-assemble into small and uniform nanomicelles, which accumulate in tumors for effective PET imaging. Benefiting from the combined dendrimeric multivalence and EPR-mediated passive tumor targeting, this nanosystem demonstrates superior imaging sensitivity and specificity, with up to 14-fold increased PET signal ratios compared with the clinical gold reference 2-fluorodeoxyglucose ([¹⁸F]FDG). Most importantly, this dendrimer system can detect imaging-refractory low–glucose-uptake tumors that are otherwise undetectable using [¹⁸F]FDG. In addition, it is endowed with an excellent safety profile and favorable pharmacokinetics for PET imaging. Consequently, this dendrimer nanosystem constitutes an effective and promising approach for cancer imaging. Our study also demonstrates that nanotechnology based on self-assembling dendrimers provides a fresh perspective for biomedical imaging and cancer diagnosis.

Near-Infrared Semiconducting Polymer Brush and pH/GSH-Responsive Polyoxometalate Cluster Hybrid Platform for Enhanced Tumor-Specific Phototheranostics

Tumor-specific phototheranostics is conducive to realizing precise cancer therapy. Herein, a novel tumor microenvironment (TME)-responsive phototheranostic paradigm based on the combination of semiconducting polymer brushes and polyoxometalate clusters (SPB@POM) is rationally designed. The acidic TME could drive the self-assembly of SPB@POM into bigger aggregates for enhanced tumor retention and accumulation, while the reducing TME could significantly enhance the NIR absorption of SPB@POM for significant improvement of photoacoustic imaging contrast and photothermal therapy efficacy. Therefore, the smart pH/glutathione (GSH)-responsive SPB@POM allows for remarkable phototheranostic enhancement under the unique TME, which has potential for precise tumor-specific phototheranostics with minimal side effects.